The present invention relates generally to telecommunication systems and, more specifically, to multi-mode telecommunication terminal devices arranged for accessing a plurality of different telecommunication systems or networks.
Due to the deregulation of the telecommunications market, at present telecommunication services such as telephony are provided by a number of different operators using the same and/or separate telecommunication networks.
Wireline telephone communication is mainly provided by the established telecommunication operators via the Public Switched Telephone Network (PSTN). Besides wireline communication these operators also provide wireless or mobile communication over special radio telecommunication networks such as the well known analogue cellular radio telephone networks designated AMPS, ETACS, NMT-450 and NMT-900 which have been deployed throughout the world, and/or digital radio cellular systems such as designated IS-54B in North America and the pan-European Global System for Mobile telecommunications (GSM). New operators mainly provide public telecommunication services over such cellular radio telecommunication systems. These systems, and others, are described, for example, in the book titled xe2x80x9cCellular Radio Systemsxe2x80x9d, by Balston et al., published by Artech House, Norwood, Mass., 1993.
A special form of radio telecommunication is called cordless communication, ranging from simple residential cordless telephones to business cordless systems capable of serving hundreds or even thousands of cordless communication units across (large) offices, production halls etc. Analogue cordless telephones are designated CT0, CT1 and CT1+. Digital cordless systems are designated CT2, CT2-CAI, CT3, PHS and DECT (Digital Enhanced Cordless Telecommunications). CT3, PHS and DECT use TDMA (Time Division Multiple Access) as their transmission technique, whereas CT2 operates under FDMA (Frequency Division Multiple Access). Besides these access techniques, in particular in North America, spread spectrum access is used for cordless communication. CDMA (Code Division Multiple Access) is another digital access technique which can be used for cordless communication. An elaborated discussion on DECT can be found in a paper by D. Akerberg, xe2x80x9cNovel Radio Access Principles Useful for the Third Generation Mobile Radio Systemsxe2x80x9d, The Third IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, Boston Mass., Oct. 19-21, 1992.
In particular the digital cordless telecommunication systems have been proven to be very suitable for providing telecommunication services over Cable TeleVision (CaTV) networks and to provide a type of Personal Communication Services (PCS) or also called Cordless Terminal Mobility (CTM). This is basically a mobile telecommunication service that covers a whole town or city. Customers of this service are able to carry their mobile communication units (e.g. telephone handsets) with them and can make calls in the coverage area of the service. It will be appreciated that such new telecommunication systems provide new operators an excellent opportunity to operate telecommunication services over other networks than the PSTN such as CaTV networks, power cables, etc. and, of course, through the air.
In future, a user will subscribe to those telecommunication systems which best meet his/her demands for communication and, of course, with such operator providing the most attractive price and/or grade of service, for example. Accordingly, a particular user can have a PSTN subscription from operator X, a GSM subscription from operator Y and a CTM subscription from operator Z, for example.
Although there is trend to integration of, for example, radio telephone terminals arranged for multi-mode operation, such as disclosed by GB-A-2,225,512, i.e. a single radio telephone terminal capable of accessing a particular network operating in accordance with a particular mode, such as GSM or DECT, in practice among subscribers there will be a need to access a particular network or telecommunication system or mode using either one of the single mode telecommunication subscriber terminals available to him/her. This, for example, to always benefit from the most cost effective mode of communication in a particular case.
Besides the subscribers, it is also very advantageous for operators to have an opportunity to force subscribers to use a particular network or system (i.e. mode) for example in case of network problems, to levitate the use of a particular network during busy hours in such network, etc.
International patent application WO 95/23485 discloses a so-called xe2x80x9cmulti-mode communication systemxe2x80x9d, comprising a base unit having transceiver and control means to place telephone calls according to any of the known radio communication standards such as GSM, PCH, AMPS, NMT450, CT1/CT2/CT3 etc. Communication through either one of these radio protocols can be established from a cordless or cellular handset connecting to the base unit. The base unit has several built-in radio transceiver and control means for connection to the different radio telecommunication networks, rendering the unit relatively expensive and technically complex.
EP-A-0,660,628 and WO 94/17639 disclose radio telephone equipment for connecting a cellular (GSM) telephone terminal to the fixed telephone network (PSTN). Accordingly, services such as handsfree calling, provided by the cellular telephone, can be used with the wired network. The equipment (e.g. an adapter) can connect the cellular phone by a wired or wireless linkon and may also be integrated into the cellular phone. However, access of the cellular network from a different wireless communication system or equipment such as a cordless subscriber terminal, for example, is not disclosed nor suggested.
It is an object of the present invention to present a cost effective and easy to implement solution for an integral provision of telecommunication modes and services provided to a subscriber via a plurality of wired and wireless networks.
It is a further object of the present invention to present a cost effective and easy to implement solution for an integral provision of telecommunication modes and services provided to a subscriber over a plurality of networks operated by the same or a plurality of separate operators.
According to the present invention there is provided a multimode telecommunication terminal device, comprising a plurality of interfaces for accessing a plurality of wired and/or wireless telecommunication networks from a plurality of subscriber telecommunication terminal units, and control means operatively connected to these interfaces, the control mean comprise switching means. The terminal device according to the invention is characterized in that the switching means operatively interconnect the interfaces to provide access to the plurality of wireless networks via corresponding wireless subscriber terminal units operatively connected to a corresponding interface.
The multi-mode telecommunication terminal device of the invention provides the interconnection at the subscriber end of several telecommunication networks, such as but not limited to wireline networks, cellular radio communication networks and cordless telecommunication networks.
Access to the wireless networks is advantageously provided using the radio transceiver and control means available in the several subscriber radio terminal units (e.g. mobile and/or portable radio telephones) if connected to the corresponding interface of the multi-mode telecommunication terminal device.
The present invention provides interconnection of networks at the subscribers"" end, such that calls from and towards the subscriber end are routed through the several networks or telecommunications systems available to a user.
With the device according to the invention, the operators need not to develop or invest in (additional) switching and transceiver and radio control means at the network sides in order to access networks or to route calls through the several networks, which would require additional communication links and means.
In an embodiment of the terminal device according to the invention, in order to route calls through the networks available to a subscriber, the switching means comprise processing means arranged for processing signaling information from at least one of the interfaces, the signaling information being indicative of the access to a particular network. Accordingly, by signal information received at the terminal device a required interconnection of networks can be established.
The interfaces of the terminal device may comprise network interfaces for the connection of networks and terminal interfaces for the connection of subscriber terminal units, such as telephone units. The signaling information may be generated by an operator, for example, and received through a network interface and/or generated by the subscriber and received through a terminal interface, for example. In the latter case appropriate signaling information may be generated either automatically or manually such to establish, in each case, a least cost routing of a call through one of the available networks or to give preference to a particular operator or network. With such signaling information, operators can force a call to be placed through the cellular network, for example, in case the wireline network is overloaded, or to provide certain services to a subscriber which are available in the one but not in the other network.
It will be appreciated that the terminal device according to the invention provides a very flexible and cost effective solution to both the subscribers and the operators to gain maximum benefit from the subscriber equipment and networks available.
In a preferred embodiment, an interface of the terminal device according to the invention comprises a radio access unit, in particular a radio access unit operating in accordance with a cordless radio communication standard such as the Digital Enhanced Cordless Telecommunications (DECT) standard.
With this embodiment, at the subscriber premises, calls can be received and placed through the cordless interface, whereas the subscriber may select either one of, for example, the PSTN wireline network or a cellular radio network to complete a call with a remote subscriber.
In a very advantageous embodiment, the multi-mode terminal device of the present invention comprises a terminal interface arranged for receiving a wireless subscriber unit, such as a cellular radio telephone terminal unit, for example a GSM telephone handset. By connecting a cellular telephone to this terminal interface the cellular telephone can be used as the interface to the cellular network without requiring cellular transceiver and communication control means in the multi-mode terminal device itself.
Instead of a cellular radio terminal unit the wireless terminal interface may be arranged to operate with any other radio terminal unit providing access to a network, such as but not limited to a CTM network, for example, operating under the DECT standard.
The above-mentioned and other features and advantageous of the invention are illustrated in the following description with reference to the enclosed drawings.